Imaging may extend golden window for stroke treatment

CT Angiography Source Images (CTA-SI) may help predict which patients suffering from ischemic stroke will benefit from endovascular therapy, according to preliminary results of the Stroke Treatment and Revascularization Therapy (START) trial presented July 24 at the Society of NeuroInterventional Surgery’s annual meeting in San Diego.

The researchers reported positive clinical outcomes in 48 percent of patients in the trial, which used advanced imaging rather than the conventional 3- to 4.5-hour time window, to inform treatment decision-making.

“This is a way to extend the golden window,” Don Frei, MD, director of neurointerventional surgery, Radiology Imaging Associates at Swedish Medical Center in Denver, said in an interview. Although devices used to open arteries continue to improve, patient outcomes have lagged behind, he continued.

The researchers’ hypothesis was simple; physiologic imaging data might provide a way to better select patients for treatment by providing physicians with information about the patient’s circulation.

Early ischemic changes on a non-contrast CT as measured by the Alberta Stroke Program Early CT (ASPECTS) score have been shown to predict response to endovascular therapy. To date, however, definitive studies proving the value of CTA-SIs in assessing stroke treatment outcomes had been lacking.

Frei and colleagues attempted to fill the void, designing a multi-center, prospective trial to examine the role of advanced imaging data in predicting endovascular treatment outcomes.

Study criteria required that patients show evidence of large vessel occlusion within eight hours of symptom onset and a NIH Stroke Scale (NIHSS) score of 10 or more. Those who presented within three hours must have been ineligible or not responsive to intravenous drug therapy.

The imaging method included in the study was at each center’s discretion and included non-contrast CT, CTA-SI, CT perfusion or MRI diffusion imaging. The preliminary analysis focused on the CTA-SI results for 77 patients.

However, outcomes differed based on pre-specified ASPECTS scores: 0-4 (large infarct), 5-7 (medium infarct) and 8-10 (small infarct). The rate of good outcomes was 20 percent for patients with ASPECTS 0-4, but 55.8 percent for 5-7 and 64.3 percent for 8-10. Adjusting for age and stroke severity and comparing ASPECTS 0-4 with the ASPECTS 5-10 group, pre-ASPECTS 5-10 was an independent predictor of good outcomes, the researchers explained.

“This tells us we can use advanced imaging to better select patients. We don’t need arbitrary time windows. We can individualize treatment based on collateral flow in many patients,” Frei said.